Battery is new regulator is new stator is new, battery takes charge very well, i just turn the key to on for 20 seconds and turn it off. i just lost 70

Question edited for clarity.
Question moved from Cars and Trucks.

Lithium Ion batteries are not suitable for motorcycles despite what it says on the label and advertising. The Scotty Kilmer YouTube Channel did a video on it 2 says ago! The technology is different the maker did not design the electronics and the computer for Lithium Ion.

You can damage electrical components if you do not run the correct voltage battery. If your battery is below 12 volts replace it. If you take off the seat you can easily test the stator with a volt meter. Find the stator plug with three yellow wires. You should have continuity between any combination of the yellow wires. You should have no continuity between any of the yellow wires and ground. That is the test of a good stator. If your bike is still losing charge after those checks , you are probably looking at a new regulator/rectifier.

it is most lightly the stator or voltage regulator in your charging system not charging your battery while running, thus runs the battery dead. If your battery is completely drained, which usually is the sign when you have no lights and backfires and the battery has no juice left to support the spark plugs, and finally gives up, and thus won't take a jump. This is a common problem. Battery needs to go on a charger and fully charged before you can conduct any electrical output test from the stator or voltage regulator. Just happened to me again this week. Hope this helps.

check your alternator/stator plate is putting current to the battery my guess is its goosed / multimeter across batery terminals should read 14.2 volts when engine is running if not its stator plate /check all terminals 1st with wd40 then chack again if it still persist then its ur stator burnt a coil

First, take your battery somewhere and have it load tested. Fat Boys are tough on batteries as the battery sits in the "horseshoe" oil tank and is subjected to high temperatures due to the hot oil in the tank. Battery life is typically two years although I've seen some go longer and some not last that long. Have the battery tested before you start spending money.

To check the stator, you unplug the regulator at the engine case. Down inside the plug you'll see some electrical connectors. Connect a DVOM (digital volt ohm meter) to these connectors (one lead to eac pin) and put the meter in the 50 volt or higher range AC voltage. This is important that your meter be set to measure AC voltage because at this point, the voltage is indeed an Alternating Current voltage coming out of your alternator. Start the engine and bring it to a high idle. You should be reading over 20 volts AC. The book says that you should read 12-18 volts per 1000 engine RPM. If your engine is turning 2000 rpm, your meter should read 24-36 volts AC.

To test the regulator, first charge your battery to a full charge. Then connect your DVOM across the battery, red to positive, black to negative. Put the meter in the 20 volt DC range. Start the bike and bring it to a high idle. The voltage will start at somewhere around 12.5 volts and climb to about 14.5-15 volts. This would indicate that the regulator MAY be alright.

Now, have you changed any of the lights on your Fat Boy? I've seen people change and add lights to the point where their alternator could no longer put out the current necessary to handle the load. If this is the case, you may need a higher out charging system.

I don't know where you're located but $260 seems quite high for a voltage regulator.

voltage regulator may not be charging...gain access to battery and take reading with key off ..should read 12.6v or better...then turn on key and see if lights put on a load and voltage drops..then start engine and crank to 300rpm and with votmeter you should see it raise uo quickly to about 13.5 or 14v and immediate drop back down to about 13v ,,,if you got a decent battery,,,this will prove that the regulating system works. if not your stator is bad...find the connector to the stator and check any two wires leading to the stator for .1to1ohm this is a good reading, if not stator is bad. you said you had 4v is that correct? because if it is, your battery is shot and needs replacement.